45ACP Experiment Update #1

https://www.facebook.com/USAMU1956/posts/10155859064049734

From the AMU

Handloading Hump Day
Getting Started in Handloading, Part 47:
Service Pistol, Outdoor Pistol, and Accurate Ammo
 
16 August 2017
 
 
(HL)  “And now, for something completely different…”  ‘Tis Summer -- the season for Service Pistol shooting!  Our Handloading Shop members have enjoyed Service Pistol competition, discussing pistol accuracy and sharing the camaraderie of competitive shooters from all over.  In that spirit, this week’s topic will focus on handloading for best pistol accuracy, rather than our usual rifle-oriented information.
 

One often-overlooked aspect of handloading highly-accurate pistol ammunition is the amount of crimp used, and its’ effect on accuracy.  (NOTE: this article pertains to loading for semi-autos – revolver crimp techniques address some quite different issues.)   Briefly, different amounts of taper crimp are used with various handloads to obtain best accuracy.  The amount is based on bullet weight, powder burn rate and charge, plus other factors such as neck tension.  During machine-rest testing of experimental Service Pistol ammunition, many variables are examined.  Among these, it is not unusual for our Shop to vary a load’s crimp in degrees of 0.001” and re-test for finest accuracy.

 
One question that often arises is, “How do I measure the taper crimp I’m putting on my cartridges?”   Using the narrow part of one’s dial caliper jaws, carefully measure the case diameter at the exact edge of the case mouth on a loaded cartridge.  It’s important to take several measurements to ensure consistency.  Also, be sure to measure at several places around the case mouth, as wall thickness can vary.  After measuring 2-3 cartridges with a given crimp setting, one can be pretty confident of the true dimension and that it can be repeated later, if needed.  
 
 
However, for good results, one must use brass from one maker, due to variances in case wall thickness.  For example, the same degree of crimp that is imparted by a measurement of 0.471” with Brand X brass will be achieved using 0.469” crimp with brand Y.  Thus, for best accuracy, using brass from the same manufacturer is important – particularly for 50 yard Slow Fire.  In a perfect world, it is better still to use brass from one lot number if possible.
 
 
Brass is important to pistol accuracy.  While accurate ammunition can be loaded using brass of mixed parentage, that is not conducive to finest results, particularly at 50 yards.  It is important for the serious competitor to pay attention to his brass – even if only the “Slow Fire” portion.  By segregating brass as described above, and additionally keeping track of the number of times a given batch of cases has been fired, one can help ensure case neck tension and case length are most uniform.  
 
 
Uniformity of the case Overall Length (OAL) as it comes from the factory is also important to achieving utmost accuracy.  More uniform case lengths (best measured after sizing) contribute to greater consistency of crimp, neck tension, ignition/burn of powder charge, etc.  Cartridge case-length consistency varies from lot to lot, as well as by maker.  Some manufacturers are more consistent in their dimensions than others, and also in the hardness/ductility of their brass.  

Given the volumes of ammunition consumed by active pistol competitors, using inexpensive, mixed surplus brass for practice, particularly at the “short line” (25 yards), is understandable.  The 10-ring there is relatively generous – especially for a well-trained shooter with an accurate pistol and load.  However, for the “long line” (50 yards), purchasing and segregating a lot of high-quality brass to be used strictly for slow-fire is a wise idea.  Similarly, pay attention to primer brands, powder types and charges, etc.  Evaluating accuracy with a Ransom or other machine rest at 50 yards can quickly reveal the effect of changes made to handload recipes.  
 
 
Bullets are another vital issue.  First, there is the question of Full Metal Jacket vs. Jacketed Hollow Point.  A friend of this writer spent decades making and accuracy-testing rifle and pistol bullets during QC for a major bullet manufacturer.  In his experience, making highly-accurate FMJ bullets is much more difficult than making highly-accurate JHP’s, in large part due to the way the jackets are formed.  Small die changes can affect accuracy of FMJ lots dramatically.  
 
 
The CMP now allows “safe, jacketed ammunition” in Excellence-in-Competition (EIC) Service Pistol matches, although wadcutter ammunition is prohibited.  Thus, the option to use very accurate JHP designs greatly simplifies the life of CMP Service Pistol shooters in pursuit of the prestigious Distinguished Pistol Shot badge.
 
 
During the days when FMJ bullets were required, accuracy-testing each lot and setting aside the best available for 50 yard use was very important.  This practice is still wise; however, finding very-accurate lots of JHP’s tends to be much easier.  Those who must use FMJ’s should buy the largest quantities of known-accurate bullet lots possible, to ensure adequate availability and quality.
 
 
Hopefully, these tips will be helpful to any pistol shooters interested in accurate handloads, not just “Bulls-eye” shooters.  Small tweaks to one’s normal routine can pay big dividends in improved accuracy and make practice and competition more rewarding.  
 
Stay safe, and good shooting!
 
[PHOTO:  Small changes in ammunition dimensions can have a surprisingly important effect on accuracy!]
 
#Handloading, #Accuracy, #PistolTeam, #CampPerry, #InterservicePistol, #ArmyShooters, #USAMU, #NRA, #USMC , #USNAVY, #USAF, #NationalGuardTeam, #ReserveTeam, #EICMatches, #DistinguishedPistol,

Hopefully one day the AMU will consolidate all of their hand loading articles from Facebook into a book or post them together. They have had some very interesting articles.

Yeah what jglenn21 said.

You can just copy and past them into a word doc

Then create a PDF and make us all happy!

And, another article with not one single bit of test data, only statement of "fact" with nothing to back it up.
If you want to discuss the importance of some magic crimp number, then do the tests and report the results. Otherwise, it is only hand-waving.
Also, I have found that for .45 Auto, most things just don't matter—the round is accurate almost no matter what and fine-tuning simply doesn't show up on target; however, in 9x19, I have found that I can take a load that shoots about 4" at 25 yards and shrink the groups size by ONLY using my longest cases.
Using one of my "pet loads," I sized my cases and sorted by length (NOT by head stamp) and divided by those that were longer than 0.749" and those shorter. Thus, my own doubt that trimming cases that head space on the case mouth will produce more accurate ammunition.

Bullet Mfg.	Bullet Weight	Bullet Type	Powder	Powder Weight	Primer	COL	Gun	Case Length	Accuracy
Nosler	115	JHP	Unique	6.0	Rem 1 ½	1.025	Para Carry-9	≤0.749	2.79
Nosler	115	JHP	Unique	6.0	Rem 1 ½	1.025	Para Carry-9	≤0.749	4.10
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	≤0.749	2.30
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	≤0.749	1.48
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	≤0.749	3.12
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	≤0.749	1.65
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	≤0.749	2.93
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	1.90
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	2.29
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	2.02
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	2.30
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	1.99
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	1.85
Nosler	115	JHP	Unique	6.0	WSP	1.025	Para Carry-9	>0.749	1.23
							Case	Avg.	S.D.
							Short	2.62	0.90
							Long	1.94	0.36

The point of the AMU article is that you need to test your ammo in your gun. Changes in variables can mean changes in group size. I mentioned this before and since I did others have found out too. That magazines have an effect on accuracy and group size. While I only fired 50 rounds in testing. I discovered that one of my magazine consistently shot a vertical rather than round group at 50 yards. One magazine would shoot 1-3/4 inches in a round group with my long line load. The other would shoot to the same center but the group would be 2-3/4 inches. These are gunsmith tuned Metalform magazines.

Maybe a gunsmith could explain how the mag could impact the accuracy for me.  I can understand feed and eject issues.

The magazine springs will vary on the amount of pressure they exert on the follower. This pressure/force pushes cartridge into the bottom of the slide disconnector rail. Different pressure equals different slide velocities in and out of battery. Same force pushes cartridge into feed lips. This will cause a different slide velocity as well. When cartridges are stripped out of magazine during feeding is it smooth or rough? Does one magazine feed perfectly and another has a speed bump because it releases too soon or too late? Your adding variables using more than one magazine. You could also get lucky and have 2 that are just right and you get no group shift, etc. Forgot to mention that erratic cycling can make a sub 1.5" pistol shoot 3+ inches. So I never mix magazines and use the same one with one pistol......ever! It's how I was taught and I don't deviate.
Jon

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I hate statistics, they burn up too much ammo! lol

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james r chapman wrote:I hate statistics, they burn up too much ammo! lol

They also tend to blow holes in the pre-conceived notions we think are important.

Statistically if you buy 100 Powerball tickets you increase your odds of winning!

Yeah, right. Lol

james r chapman wrote:Statistically if you buy 100 Powerball tickets you increase your odds of winning!

Yeah, right. Lol

Actually, if you buy 100% of the Powerball tickets, you have a 100% chance of winning all the payouts. BUT not of winning the biggest prize. nor getting your money back!

I like the statement, "The Lottery is a tax on people who are bad at math"

Jon Eulette wrote:The magazine springs will vary on the amount of pressure they exert on the follower. This pressure/force pushes cartridge into the bottom of the slide disconnector rail. Different pressure equals different slide velocities in and out of battery. Same force pushes cartridge into feed lips. This will cause a different slide velocity as well. When cartridges are stripped out of magazine during feeding is it smooth or rough? Does one magazine feed perfectly and another has a speed bump because it releases too soon or too late? Your adding variables using more than one magazine. You could also get lucky and have 2 that are just right and you get no group shift, etc. Forgot to mention that erratic cycling can make a sub 1.5" pistol shoot 3+ inches. So I never mix magazines and use the same one with one pistol......ever! It's how I was taught and I don't deviate.
Jon

Jon,

Will the pressure on the bottom of the slide impact how the lock up happens and relative position of the parts at lock up?  I thought that the accuracy would be mostly dependent on the locked up position. Based on your description would the last round be impacted differently since there no rounds left in the mag to impact the slide the same way as the 4 previous rounds?

Shouldn't affect lockup. Yes as each cartridge is loaded into chamber the spring pressure lessens/reduces. Typical flyers are 1st round (loaded by hand) and last round. Most people will leave shot 5 in chamber and reload magazine for shots 6-10 when Ransom resting to try and not get the flyer in their group.
Jon

Thank you Jon.  The light bulb just went on.  I have wondered what was causing these Flyers for a long time and you just explained it.  Has it ever been tried putting a plug below the follower so that fifth round has more pressure or would it just mess up the pressure on the first round.  I have wondered why these states that are not wanting to outlaw any mags over 10 rounds just don't just allow the mags to be plugged like I did with my duck gun.  Don

Jon Eulette wrote:Shouldn't affect lockup. Yes as each cartridge is loaded into chamber the spring pressure lessens/reduces. Typical flyers are 1st round (loaded by hand) and last round. Most people will leave shot 5 in chamber and reload magazine for shots 6-10 when Ransom resting to try and not get the flyer in their group.
Jon

If there is no affect, then at lockup the pistol is back to the same state it is for every round in the mag.  I am still struggling to understand how at this point the pressure on the bottom of the slide from the mag can impact the trajectory of the bullet. Your goal as a gunsmith is to get all of the moving parts in a 45 to return to as close as possible the same relative position at lockup so that each round has the same trajectory.

Consistency of how pistol goes into battery! Inconsistent cycling equals poor groups! Try single loading 10 shots into 1911 while Ransom resting and you get huge groups. Pistol will cycle out of battery differently as well. A newly built pistol (one that I built) will typically vertical string slightly because its still slightly breaking in lower barrel lug to slidestop pin. It cycles in snd out of battery slightly inconsistent. Once they seat in the vertical stringing goes away.
Jon

the Marvel disconnector slot is an example of trying to have consistent cycling..
 after the first round is fired all cycles had the disconector being held down by the trigger.. when you release the slide manually the diconnector is up and slightly alters how the gun feeds.. the slot smooths  this part of the cycle.  only works for the first round.

while its a pain to learn the Ransom will teach you quite a bit about magazines and being consistent. find a mag that works well and use for the long line..